As technology penetrates further into all aspects of people's daily lives, wearable sensor devices (e.g., pedometers, smart watches, sport watches, fitness trackers) have recently become more personalized, becoming tailored to fit unique lifestyles and scheduled for each user. For example, a fitness tracker becomes quite popular in tracking daily fitness results and setting goals. The wearable sensor devices are also useful for medical geriatric or ambulatory monitoring of individuals in order to assess levels of independence.
Although a high level of physical activity recognition accuracy has been achieved in the past using sensors (or sensor arrays), these approaches are not very effective when sensor placement is less optimal. To address this problem, additional onboard sensors (such as gyroscopes and magnetic compasses) can help disambiguate human motion data and greatly improve recognition accuracy.
However, these additional sensors consume significantly more electrical power, and drastically reduce the battery life of the wearable system. In general, as indicated in this disclosure, the power consumption rate of these additional sensors is too large to leave active over the course of a day while tracking a user's activities. To save the power, it is important to know when to activate and deactivate the additional sensors. The additional sensors are activated only as needed in order to attempt to maintain pre-set recognition accuracy while keeping the power consumption of the wearable system minimized as much as possible. A desired goal for the wearable sensor devices is not only to maximize the physical activity recognition accuracy, but also to simultaneously minimize the electrical power consumption onboard the wearable sensor devices.
The disclosed wearable systems and methods are directed to solve one or more problems set forth above and other problems.